The production of impregnated fibers and the application of thermoplastic resins to the fibers is well-known. Such fibers are coated with the thermoplastic resin after the fiber strand has been formed.
Sizing compositions employed as coatings for glass fibers have conventionally been applied to the surface of the glass fibers after the glass fiber has been formed. Typically, it is necessary to first produce the glass fibers by providing a thin layer of a size composition to the surface of the bare glass fibers. The size composition must be compatible with the glass fiber and the resin which is subsequently applied to the sized fiber. The size composition serves to improve the bonding relationship between the glass fibers and the polymeric or thermoplastic resins. The glass fibers are then collected into a strand and the strand is wound around a take-up bobbin to form a substantially cylindrical package, conventionally termed a "yarn package". The yarn package is then air dried or subjected to elevated temperatures in order to dry the size composition applied to the surface of the glass fibers. The glass fibers are thereafter impregnated with the thermoplastic resin to form an impregnated yarn or cord.
However, it is difficult to produce a liquid crystal polymer impregnated glass fiber strand. Liquid crystal polymers cannot be dissolved in the size composition solvents normally used in producing impregnated fibrous strands. Therefore, the liquid crystal polymer thus cannot be applied to a filament using a solvent impregnation process. In addition, the conventional melt impregnation process cannot be used to produce a glass fiber strand impregnated with a liquid crystal polymer since a specific size composition must be used which does not allow for the production of highly loaded liquid crystal polymer impregnated glass strands having optimum mechanical properties such as high strength.
It would be beneficial if a glass fibrous strand impregnated with a liquid crystal polymer could be produced which would have good integrity and optimum mechanical properties. Such impregnated strand would be especially useful for high performance and use items.
Considerable time and expense would be saved if a size composition useful for impregnating glass strands with a liquid crystal polymer resin were available which could be applied during the fiber forming process without the need for non-aqueous solvents, fluidized beds, sheaths or time-consuming manufacturing processes.
Moreover, it would be beneficial if a size composition could be employed which, when directly blended with the liquid crystal polymer resin during the glass fiber forming process, produces a substantially pure liquid crystal polymer impregnated glass strand.